Synthesis and design of biomass-derived heteroatom-doped hierarchical porous carbon systems for high-voltage supercapacitors

Abstract

Porous carbon systems rich in heteroatoms can be used to achieve high energy density under conditions of high power density. However, it is difficult to evaluate the structure–effect relationships between the types of heteroatoms present in the systems and the electrochemical properties of the materials, leading to the trial-and-error approaches are still used to date for the development of high-performance supercapacitors. Herein, we report the process of synthesis of a series of biomass-derived carbon systems doped with heteroatoms and characterized by large specific surface areas and 3D hierarchical porous structures. We analyzed experimental evidence and results from theoretical simulations to establish doping principles with predictive electrochemical performance. The doping of N, S and O atoms in carbon materials successfully broadens the operating voltage (up to 1.8 V) in aqueous electrolytes and improves the landscape of capacitive ions adsorption. The doped materials are characterized by high energy density (25.2 Wh kg−1 at 180 W kg−1) and exhibit excellent cycling performance (97.6% capacity retention after 20,000 cycles). Our work provides a reference for rationally designing and tuning the heteroatom combination mode and pore structure distribution associated with the materials to develop advanced heteroatom-doped carbon electrodes.